Bivalvia

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Bivalvia Cephalopoda
Welcome to the home of Bivalvia and Cephalopoda.
My name is Tim Dillavou and these pages are
devoted to giving some background information on
bivalves and cephalopods. They will also give
some more detailed information on a few species I
encountered during a marine ecology class at
University of Washington-Tacoma during the spring
of 2007.
Bivalvia
Species Encountered (Bivalves)
Chlamys rubida(Pacific pink scallop)
Mytilus californianus(California mussel)
Cephalopoda
Species Encountered (Cephalopods)
Enteroctopus doflieni(giant Pacific octopus)
References
Webpage created by Timothy Dillavou on 05-23-2007

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Bivalvia

• Kingdom animalia
• Phylum mollusca
• Class Bivalvia
• Characteristics
• Bivalve refers to having a shell with two halves
  or valves.
• All bivalves have rigid shells to provide support
  for their soft bodies. 
• Bivalvia is the only molluscan class
  characterized by the absence of a radula.
• Live
• Marine or freshwater
• In or on top of sediment (epifaunal or infaunal)
• Life span varies
• Size 2mm to over 4 feet (giant clam of the south
  pacific)
• Feeding/Respiration
• Most are filter feeders defined by a gill
  structure
• Some are scavengers or predators
• consume phytoplankton and other tiny organic
  matter that flows through their gills. 
• gills function both in respiration and in
  straining out food particles.
• mussels can filter 10-15 gallons of water per
  day.
• Locomotion

Species Encountered
Chlamys rubida(pacific pink scallop)
Mytilus californianus(California mussel)
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Tresus nuttalli (pacific gaper)
Crassostrea gigas (Japanese oyster)
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Species Encountered(Bivalves)
Scientific name Common name Found Observations
Chlamys rubida Pacific pink scallop Friday Harbor (otter trawl) sponge covering one side, ears unequal size, swim
Clinocardium nuttalli Nuttallis cockle Fox Island Willapa Bay oval shell, light brown, found at 12 depth
Modiolus modiolus Horse mussel Friday Harbor (otter trawl) brownish/black shell, Size 5 long
Mytilus californianus California mussel Friday Harbor (Cattle Point Argyle Point), Olympic Coast (Salt Creek) bluish/black, attached to low rocks in colonies. rounded ridges on shell
Mytilus trossulus Bay mussel Point Defiance (floating dock) Fox Island smooth wedge shaped shell, attached to pilings w/byssal threads
Crassostrea gigas Japanese oyster Fox Island Friday Harbor (False Bay) irregular ridged shell, grayish/white
Ostrea lurida Native oyster Fox Island whitish gray
Pododesmus macrochisma Rock oyster Point Defiance (floating dock) Friday Harbor (Salt Creek) jingle shell, hole in middle of lower shell, grayish
Tresus nuttalli Pacific Gaper Willapa Bay Friday Harbor (False Bay) siphon yellowish/tan, gaper pea crab inside clam
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Chlamys rubida(Pacific pink scallop)

• Description 
• prominent ribs on each valve
• grows to about 6 -7 cm long.
• swim when threatened
• many eyes around the outside, which perceive
  light and direction. 
• One side of shell is covered with a symbiotic
  sponge. 
• Geographical Range
• Alaska to San Diego, CA uncommon S of Puget
  Sound.
• Depth Range
• low intertidal to 300 m mainly subtidal
• Habitat
• rocky or gravel/mud bottoms.
• Life span
• up to 6 years. 
• Reproduction
• externally when eggs and sperm are released into
  water
• Humans uses
• harvested by recreational commercial fishermen
  because highly desirable seafood.

Photos by Hannah Julich, May 2007
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Mytilus californianus(California sea mussel)
Photo by Dave Cowles, Little Corona del Mar, CA
March 2005

• Description
• color bluish/ black, concentric growth lines
• shell to about 8 inches long
• Geographical range
• Alaska to southern Baja California
• Depth Range
• mainly in intertidal zone on outer coast
• Habitat
• Abundant, on surf-exposed rocks and pier pilings
  in colonies for protection
• Feeding
• Filter feeder, prefer to eat fine organic
  material and plankton
• Life span
• 10-100 years
• Reproduction
• Male releases sperm into water and enters female
  when water is siphoned over gills

Photos by Bonnie Becker 2007
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Cephalopoda

• Kingdom animalia
• Phylum mollusca
• Class cephalopoda
• Two subclasses
• Coleoidea squid, cuttlefish, and octopus
• Nautiloidea nautiluses
• Characteristics
• A funnel derived from the molluscan foot,
  circumoral arms that are probably derived from
  the molluscan head, chitinous beaks
• Habitat
• all marine, In all seas at all depths, Octopuses
  are solitary living in cracks and crevices but
  squid have been known to swim in large groups
• Life span
• 1-3 years (except for nautilus up to 15 yrs)
• Feeding
• carnivores crustaceans, fish, gastropod
  molluscs
• Respiration
• gills
• Locomotion
• walk with use of tentacles (octopus), lateral
  fins to swim (cuttlefish), jet propulsion (squids
  almost use exclusively)
• Shell/Skeleton

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Species Encountered(Cephalopods)
Scientific name Common name Found Observations
Enteroctopus doflieni Giant Pacific octopus Olympic coast (Salt creek), Seattle aquarium Only tentacle found at Salt creek (still changing color suctioning)
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Enteroctopus doflieni(giant Pacific Octopus)

• Description
• largest species in the world, up to 400 lbs and
  25 feet arm span
• Geographical range
• Pacific ocean
• common in Puget Sound
• Depth Range
• intertidal to 750 m
• Habitat
• rocky crevices
• Feeding
• crustaceans, mollusks, fish
• Life span
• 3-5 years
• Reproduction
• female lays between 20,000 to 100,000 eggs and
  tends the eggs until hatched and then dies
• Human uses
• food, display in aquariums, and for use as bait
  in other fisheries

Picture by Bonnie Becker, 2007
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Picture by Greg Gilbert The Seattle Times, 2003
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References

• The University of Arizona College of Agriculture
  and Life Sciences website accessed on 03-31-2007
• http//tolweb.org/tree/phylogeny.html
• State of Washington website accessed on
  04-02-2007
• http//depts.washington.edu/natmap/mollusks
  /3bivafile.html
• Bermuda Institute of Ocean Sciences website
  accessed on 04-03-2007
• http//www.thecephalopodpage.org/
• Smithsonian National Zoological Park website
  accessed on 04-03-2007
• http//nationalzoo.si.edu/Animals/Invertebr
  ates/Facts/cephalopods/
• State University of New York College at Cortland
  website accessed on 03-31-2007
  http//www.cortland.edu/
• University of Michigan Museum of Zoology website
  accessed on 04-04-2006 http//animaldiversity.
  ummz.umich.edu/site/accounts/information/Bivalvia.
  html
• University of Hawaii at Manoa website accessed on
  04-04-2007
• www.soest.hawaii.edu

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